• Title/Summary/Keyword: energy space

Search Result 3,298, Processing Time 0.034 seconds

Analysis of Joint Multiband Sensing-Time M-QAM Signal Detection in Cognitive Radios

  • Tariq, Sana;Ghafoor, Abdul;Farooq, Salma Zainab
    • ETRI Journal
    • /
    • v.34 no.6
    • /
    • pp.892-899
    • /
    • 2012
  • We analyze a wideband spectrum in a cognitive radio (CR) network by employing the optimal adaptive multiband sensing-time joint detection framework. This framework detects a wideband M-ary quadrature amplitude modulation (M-QAM) primary signal over multiple nonoverlapping narrowband Gaussian channels, using the energy detection technique so as to maximize the throughput in CR networks while limiting interference with the primary network. The signal detection problem is formulated as an optimization problem to maximize the aggregate achievable secondary throughput capacity by jointly optimizing the sensing duration and individual detection thresholds under the overall interference imposed on the primary network. It is shown that the detection problems can be solved as convex optimization problems if certain practical constraints are applied. Simulation results show that the framework under consideration achieves much better performance for M-QAM than for binary phase-shift keying or any real modulation scheme.

The Development and Application of Habitats Environment Evaluation Model - Focused on local environmental assessment for determining priority areas for the implementation of green roof in Seoul - (생물서식지 환경평가모델 개발 및 적용에 관한 연구 - 서울시내 옥상녹화 우선 조성지역 도출을 위한 지역환경평가를 중심으로 -)

  • Yoon, So Won
    • Journal of the Korean Society of Environmental Restoration Technology
    • /
    • v.8 no.3
    • /
    • pp.53-66
    • /
    • 2005
  • The objective of this study is the classification of priority areas for the implementation of green roof by evaluating environmental deterioration in Seoul. Non-permeable pavement, air pollution, habitual floods, energy use, heat island and green space are considered in this assessment indicators. The expert questionnaire survey was conducted in order to determine the most important indicators. These indicators were then, thoroughly evaluated. As a result, high priority areas for the implementation of green roof were deduced in the following order of the districts : Jung, Sungdong, Jungrang, Youngdungpo, Jongro and Kangnam. The highest priority areas were determined to be crowded business-commercial areas. Low priority areas are analyzed in the following order of the districts : Kwanak, Nowon, Seocho and Dobong. The result of this study can be utilized for environmental planning and decision of related policies. Additionally, it can be promoted that awareness of implementing green roof of citizens, policy makers and building owners and effect of green networking between inside and outside Seoul can be increased.

A New Reference Pixel Prediction for Reversible Data Hiding with Reduced Location Map

  • Chen, Jeanne;Chen, Tung-Shou;Hong, Wien;Horng, Gwoboa;Wu, Han-Yan;Shiu, Chih-Wei
    • KSII Transactions on Internet and Information Systems (TIIS)
    • /
    • v.8 no.3
    • /
    • pp.1105-1118
    • /
    • 2014
  • In this paper, a new reversible data hiding method based on a dual binary tree of embedding levels is proposed. Four neighborhood pixels in the upper, below, left and right of each pixel are used as reference pixels to estimate local complexity for deciding embeddable and non-embeddable pixels. The proposed method does not need to record pixels that might cause underflow, overflow or unsuitable for embedment. This can reduce the size of location map and release more space for payload. Experimental results show that the proposed method is more effective in increasing payload and improving image quality than some recently proposed methods.

Design and Analysis of Lightweight Trust Mechanism for Accessing Data in MANETs

  • Kumar, Adarsh;Gopal, Krishna;Aggarwal, Alok
    • KSII Transactions on Internet and Information Systems (TIIS)
    • /
    • v.8 no.3
    • /
    • pp.1119-1143
    • /
    • 2014
  • Lightweight trust mechanism with lightweight cryptographic primitives has emerged as an important mechanism in resource constraint wireless sensor based mobile devices. In this work, outlier detection in lightweight Mobile Ad-hoc NETworks (MANETs) is extended to create the space of reliable trust cycle with anomaly detection mechanism and minimum energy losses [1]. Further, system is tested against outliers through detection ratios and anomaly scores before incorporating virtual programmable nodes to increase the efficiency. Security in proposed system is verified through ProVerif automated toolkit and mathematical analysis shows that it is strong against bad mouthing and on-off attacks. Performance of proposed technique is analyzed over different MANET routing protocols with variations in number of nodes and it is observed that system provide good amount of throughput with maximum of 20% increase in delay on increase of maximum of 100 nodes. System is reflecting good amount of scalability, optimization of resources and security. Lightweight modeling and policy analysis with lightweight cryptographic primitives shows that the intruders can be detection in few milliseconds without any conflicts in access rights.

NOx Removal of NH3-SCR Catalysts with Operating Conditions (공정조건에 따른 NH3-SCR용 촉매의 질소산화물 제거특성)

  • Park, Kwang Hee;Cha, Wang Seog
    • Journal of the Korea Academia-Industrial cooperation Society
    • /
    • v.13 no.11
    • /
    • pp.5610-5614
    • /
    • 2012
  • Performance of catalyst was studied with various operating conditions for selective catalytic reduction of $NO_x$ with $NH_3$. It is confirmed that catalysts containing Mn and Cu have a good efficiency in the usage of oxygen by the $H_2$-TPR analysis. In the case of catalyst #1, $NO_x$ conversion was decrease with the increase of reaction temperature. But in the case of catalyst #2, $NO_x$ conversion was increased and then remained constant with the increase of reaction temperature. This phenomenon is due to the difference of the $NH_3$ oxidation of both catalysts.

Enhancement in Performance of $Pt/CeO_2$ Catalysts for Single Stage Water-Gas Shift (WGS) Reaction via Controlling the Preparation Conditions (제조 조건 조절을 통한 수성가스전이 반응에서 $Pt/CeO_2$ 촉매 성능 강화)

  • Eum, Ic-Hwan;Jeong, Dae-Woon;Kim, Ki-Sun;Roh, Hyun-Seog;Koo, Kee Young;Yoon, Wang Lai
    • 한국신재생에너지학회:학술대회논문집
    • /
    • 2010.06a
    • /
    • pp.229.2-229.2
    • /
    • 2010
  • 한 단계 수성가스전이반응(Single stage water gas shift reaction)을 위해 높은 산소저장능(OSC: Oxygen Storage Capacity)을 가진 $CeO_2$를 담체로 사용하여 $Pt/CeO_2$ 촉매를 설계하였다. 촉매의 제조 조건은 촉매 활성과 매우 밀접한 관계가 있다. 따라서 $Pt/CeO_2$ 촉매에 제조변수를 다양하게 변화하여 성능을 평가하였다. 촉매 반응 실험은 공간속도(GHSV: Gas Hourly Space Velocity) $45,515h^{-1}$에서 수행하였다. 본 연구에서는 $Pt/CeO_2$ 촉매를 최적화하기 위해 촉매 제조 조건 중 소성온도, 배치 당 제조질량, 전구체 그리고 pH 와 같은 다양한 제조 조건으로 촉매의 성능을 평가하였다.

  • PDF

A study on the dynamic instabilities of a smart embedded micro-shell induced by a pulsating flow: A nonlocal piezoelastic approach

  • Atabakhshian, Vahid;Shooshtaria, Alireza
    • Advances in nano research
    • /
    • v.9 no.3
    • /
    • pp.133-145
    • /
    • 2020
  • In this study, nonlinear vibrations and dynamic instabilities of a smart embedded micro shell conveying varied fluid flow and subjected to the combined electro-thermo-mechanical loadings are investigated. With the aim of designing new hydraulic sensors and actuators, the piezoelectric materials are employed for the body and the effects of applying electric field on the stability of the system as well as the induced voltage due to the dynamic behavior of the system are studied. The nonlocal piezoelasticity theory and the nonlinear cylindrical shell model in conjunction with the energy approach are utilized to mathematically modeling of the structure. The fluid flow is assumed to be isentropic, incompressible and fully develop, and for more generality of the problem both steady and time dependent flow regimes are considered. The mathematical modeling of fluid flow is also carried out based on a scalar potential function, time mean Navier-Stokes equations and the theory of slip boundary condition. Employing the modified Lagrange equations for open systems, the nonlinear coupled governing equations of motion are achieved and solved via the state space problem; forth order numerical integration and Bolotin's method. In the numerical results, a comprehensive discussion is made on the dynamical instabilities of the system (such as divergence, flutter and parametric resonance). We found that applying positive electric potential field will improve the stability of the system as an actuator or vibration amplitude controller in the micro electro mechanical systems.

An Adaptive Fuzzy Sliding-Mode Control for Decoupled Nonlinear Systems (분리된 비선형 시스템의 적응 퍼지 슬라이딩모드 제어)

  • Kim, Do-U;Yang, Hae-Won;Yun, Ji-Seop
    • Journal of Institute of Control, Robotics and Systems
    • /
    • v.8 no.9
    • /
    • pp.719-727
    • /
    • 2002
  • We proposed a decoupled adaptive fuzzy sliding-mode control scheme for a class of fourth-order nonlinear systems. The system is decoupled into two second-order systems such that each subsystem has a separate control target expressed in terms of sliding surface. For these sliding surfaces, we define main and sub target conditions. and, we made intermediate variables which are interconnected both surface conditions from the sub target sliding surface. Then, Two sets of fuzzy rule bases are utilized to represent the equivalent control input with unknown system functions of the main target sliding surface including intermediate variables. The membership functions of the THEN-part, which is used to construct a suitable equivalent control of sliding-mode control, are changed according to the adaptive law. With such a design scheme, we not only maintain the distribution of membership functions over state space but also reduce the computing time considerably. We apply the decoupled adaptive sliding-mode control to a nonlinear Cart-Pole system and confirms the validity of the proposed approach.

Fabrication of Carbon Microcapsules Containing Silicon Nanoparticles-Carbon Nanotubes Nanocomposite for Anode in Lithium Ion Battery

  • Bae, Joon-Won;Park, Jong-Nam
    • Bulletin of the Korean Chemical Society
    • /
    • v.33 no.9
    • /
    • pp.3025-3032
    • /
    • 2012
  • Carbon microcapsules containing silicon nanoparticles (Si NPs)-carbon nanotubes (CNTs) nanocomposite (Si-CNT@C) have been fabricated by a two step polymerization method. Silicon nanoparticles-carbon nanotubes (Si-CNT) nanohybrids were prepared with a wet-type beadsmill method. A polymer, which is easily removable by a thermal treatment (intermediate polymer) was polymerized on the outer surfaces of Si-CNT nanocomposites. Subsequently, another polymer, which can be carbonized by thermal heating (carbon precursor polymer) was incorporated onto the surfaces of pre-existing polymer layer. In this way, polymer precursor spheres containing Si-CNT nanohybrids were produced using a two step polymerization. The intermediate polymer must disappear during carbonization resulting in the formation of an internal free space. The carbon precursor polymer should transform to carbon shell to encapsulate remaining Si-CNT nanocomposites. Therefore, hollow carbon microcapsules containing Si-CNT nanocomposites could be obtained (Si-CNT@C). The successful fabrication was confirmed by scanning electron microscopy (SEM) and X-ray diffraction (XRD). These final materials were employed for anode performance improvement in lithium ion battery. The cyclic performances of these Si-CNT@C microcapsules were measured with a lithium battery half cell tests.

Conformational Sampling of Flexible Ligand-binding Protein Loops

  • Lee, Gyu-Rie;Shin, Woong-Hee;Park, Hahn-Beom;Shin, Seok-Min;Seok, Cha-Ok
    • Bulletin of the Korean Chemical Society
    • /
    • v.33 no.3
    • /
    • pp.770-774
    • /
    • 2012
  • Protein loops are often involved in diverse biological functions, and some functional loops show conformational changes upon ligand binding. Since this conformational change is directly related to ligand binding pose and protein function, there have been numerous attempts to predict this change accurately. In this study, we show that it is plausible to obtain meaningful ensembles of loop conformations for flexible, ligand-binding protein loops efficiently by applying a loop modeling method. The loop modeling method employs triaxial loop closure algorithm for trial conformation generation and conformational space annealing for global energy optimization. When loop modeling was performed on the framework of ligand-free structure, loop structures within $3\AA$ RMSD from the crystal loop structure for the ligand-bound state were sampled in 4 out of 6 cases. This result is encouraging considering that no information on the ligand-bound state was used during the loop modeling process. We therefore expect that the present loop modeling method will be useful for future developments of flexible protein-ligand docking methods.